Can neutering "fail?"

[Abc12345]

I have an approx 1 year old male cat who was neutered at 6 months old. I suspect he might have had a litter of kittens in his previous home as he lived with an unspayed female cat and he himself was not neutered.

I also have a 4 month old female kitten. Today, for the first time, I saw the male cat mount the female kitten and hump her. After, he licked his private parts and went to sleep. My female kitten is not showing signs of being in heat. Her spay surgery is set for mid-September, which was the earliest date available at my vets. I'm suddenly overthinking and worried that my male cat's neuter surgery might not have been successful. Is this possible?

 

[Willowy]

Not as a general rule. I mean, cats have 2 testicles, the vet removes 2 testicles, it's pretty easy. There can be unusual circumstances, like if one testicle were retained and the vet didn't want to go inside to look for it, or something like that. Although since he didn't live with you when neutered, I suppose you might not know if something went wrong.

But even a neutered cat can and will mount other cats. And some can even achieve penetration, although that's usually those who were neutered later in life, not very likely if he was neutered at 6 months.

How did the female react when he did that?

 

[Abc12345]

Not as a general rule. I mean, cats have 2 testicles, the vet removes 2 testicles, it's pretty easy. There can be unusual circumstances, like if one testicle were retained and the vet didn't want to go inside to look for it, or something like that. Although since he didn't live with you when neutered, I suppose you might not know if something went wrong.

But even a neutered cat can and will mount other cats. And some can even achieve penetration, although that's usually those who were neutered later in life, not very likely if he was neutered at 6 months.

How did the female react when he did that?

He was with me when he was neutered. I got gim neutered as soon as I got him. The vet didn't mention any problems, so I guess he should be good.
The female kitten just struggled to get away and I had to break them up.

 

[vince]

I have a neutered male that will mount my spayed female. It happens. He acts like he doesn't quite know how to do the act, but he tries. The result is the same as yours. My female bites him and runs off.

Your boy has certainly been neutered long enough that everything should be out of his system and he won't be able to father a litter.